Gas reservoir arrangement in high voltage switch

ABSTRACT

A gas operated electrical switch for opening and closing high voltage electrical lines has a gas container containing gas at the operating pressure for actuating the switch and a reservoir containing gas at a higher pressure for resupplying the container of gas after a switch actuation. The pressure reducing means includes a small intermediate receptacle which holds gas at substantially the same pressure as in the reservoir in a quantity which is sufficient to raise the pressure in the container back to the operating pressure after a first switch actuation so as to permit a second switch actuation immediately thereafter.

United States Patent [72] Inventor Karl Krlechbaum [56] References Cited lGermany FOREIGN PATENTS [211 P 3 1 696 066 10/1964 Canada ZOO/148.5 [22] Filed June 26, 1969 9 Patented Feb. 1971 1,013,278 12/1 65 Great Britain 200/148 731 Assignee Licentia Patent Verwaltungs G-l'lLbJ'l- Pnmary Examiner-Robert Macon Frankfurt, Germany Attomey-Spencer & Kaye [32] Priority June 28,1968

- 677 8 ABSTRACT: A gas operated electrical switch for opening and closing high voltage electrical lines has a gas container containing gas at the operating pressure for actuating the switch and a reservoir containing gas at a higher pressure for resup- [54] IN plying the container of gas after a switch actuation. The pres- 9 Claim 2 D in sure reducing means includes a small intermediate receptacle gags which holds gas at substantially the same pressure as in the [52] US. Cl 200/148 reservoir in a quantity which is sufficient to raise the pressure [51] Int. Cl ...H0lh 33/54 in the container back to the operating pressure after a first [50] Field of Search 200/ 148, switch actuation so as to permit a second switch actuation im- 148.2, 148.4, 148.5, 148.7 mediately thereafter.

I 6A5 PRESSURE AGTUA TOR A T HIGH 1 1 PRESSURE 6A5 CONTAINER -2 IN T ERMfD/ATE RECEPTAC'LE I RESERVOIR 7 I 40 I /0 II 6 TIME DELA Y 5 CIRCUIT 48 4 I 'l'l COMPRESSOR PATENTEDFEB 9mm 3,562,461

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P U/QE AIIQITUATUR DR/0R ART 30 GAS F g, I

AT OPE/QA TING PRESSURE STEADV/Nfi 26 TANK 24 j? RESERVOIR COMPRESSOR 22 F 2 h -of GAS PRESSURE ACTUATOR A r HIGH PRESSURE 6A5 CONTAINER -2 /4- 3 INTERMEDIATE RECEPTACLE RESERVOIR 7 42 V V 4y I2 SP7) 8 /5 V T v 0 o T E 9 4-0 TM) 5 DELAY 45 5 CIRCUIT fi- 4 44 Q46 50 COMPRESSOR lnvenfor:

Karl, Krieclzbcmm BACKGROUND OF THE INVENTION This invention relates to gas operated electrical switches for use in opening and closing extremely high voltage electrical lines, and more particularly to a switch which may be reliably resupplied with gas for a second switching operation immediately after a first switching operation.

Gas operated switches are known which are used to open and close electrical switches in circuits operating at very high voltages. Such switches are provided with pressurized gas containers which are located adjacent the high voltage potential switches, and which are supplied with gas from a reservoir container which is electrically grounded. The gas container located adjacent the switch normally contains enough gas to serve for one switching actuation.

In applicants prior German Patent, DAS 1,244,269 there is disclosed an improved switch of this type, which is schematically illustrated in FIG. 1, hereafter described.

Referring now to FIG. 1, this prior art patent discloses a reservoir 20 containing sufficient gas for at least two switch ofi' actions and one switch-on action. The gas in the reservoir 20 is air at a pressure on the order of 200 atmospheres gauge which is substantially higher than the operating pressure, approximately 25 atmospheres gauge, of the gas actuated switch. Reservoir 20 is supplied with air by a compressor 22.

The air within reservoir 20 is reduced to the operating pressure by a reduction valve 24 and flows through a steadying tank 26. A constant pressure regulating valve 28 supplies the gas at the operating pressure to the gas container 30 through an insulating support connection 29.

The above described switch has the advantage that the reservoir 20, which is normally located adjacent to the switch, has a relatively small volume since the gas is at such a high pressure. Furthermore replenishment of the operating pressure container occurs very quickly. Moreover, a flow of scavenging air to remove moisture deposits is not required, as is necessary in some prior art devices. This is because a substantial elimination of the moisture in the air occurs as it expands from the relatively high pressure in reservoir 20 to the relatively low operating pressure used at the switch.

Sufficient time is available during switch offs for replenishing the operating pressure container so that the pressurized air may be replenished through an appropriately configured reduction valve. However, this process must be accomplished very rapidly during momentary interruptions, for example when switching from off to on and to off again. Under such circumstances the reduction valve may not be controlled quickly enough during the replenishing process so that the pressure in the operating pressure container may reach an unduly high value due to the pressurized air flowing out of the high pressure container at a high rate of pressure increase. This may result in heavy stresses being placed on the supporting insulators and on the switching chamber.

SUMMARY OF THE INVENTION Among the objects of the present invention is the provision of a gas operated switch in which the operating gas container is reliably supplied with gas at the desired operating pressure.

A further object of the invention is a provision of such an apparatus in which the gas used for a second switch ofi action has substantially the same pressure as that used for an immediately proceeding switch off action. As a result there is an increase in the cut off power of the switch as compared to prior art switches.

Briefly stated these and other objects of the invention are achieved by providing a small intermediate reservoir which is filled with gas at a much higher pressure than that within the operating gas container, and which has a volume such that its contents are just sufficient to raise the pressure in the operating pressure gas container back to the operating pressure after a first switch off action has occurred.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a gas operated electrical switch for opening and closing electrical circuits at very high voltages, as disclosed in applicants prior art German Patent DAS 1,244,269.

FIG. 2 is a schematic diagram illustrating a gas pressure switch according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 2 a gas operated electrical switch 1 according to the present invention includes a gas container 2 which is at the same electrical potential as the switch and is mounted on an insulated hollow support 3. Air at operating pressure is supplied through support 3 from an intermediate receptacle 7 which in turn is supplied from a compressor 5 through a reservoir 6. A manometer 8 is electrically connected to open a solenoid valve 9 to replenish container 2 from the intermediate receptacle 7, which contains sufficient air for one re-switching operation. Manometer 8 is also electrically connected to open a solenoid valve 10 to recharge intermediate receptacle 7 from the reservoir 6 at the same time.

Compressor 5 may be any suitable air compressor capable of charging the reservoir 6 to its desired pressure which is on the order of 200 atmospheres gauge. Reservoir 6 is electrically grounded,

Intermediate receptacle 7 is made of a glass fiber reenforced plastic material and has a relatively small volume, for example 3 liters. It is filled with pressurized air of 200 atmospheres gauge. The 3 liters are in this particular embodiment the amount which is sufficient to bring the pressure within gas container 2 back to its full value after a first switching action.

An air passage pipe 40 connects the reservoir 6 and intermediate receptacle 7. A solenoid valve 10 is mounted in this line adjacent the reservoir and a throttle I1 is mounted between valve 10 and receptacle 7. Gas line 40 continues beyond receptacle 7 with a second throttle 12, the previously mentioned solenoid valve 9, the connection to the insulated supporting connector 3, a safety valve 13, and manometers 8 and 15 being arranged in order thereon. A bypass line 42 extends about solenoid valve 9 and contains further solenoid valve 14.

The coil of solenoid valve 9 is connected at one end to one terminal 44 of a power source 46 and at its other end to line 45 which leads to one of the contacts of manometer 8. The associated contact of manometer 8, which is closed in response to a drop in the operating pressure within gas container 2 is connected to the other terminal 50 of power source 46. Valve 9 is normally closed; energization of its coil opens its valve to supply replenishing gas from receptacle 7. The contacts of manometer 8 close in response to a drop in pressure within the gas container 2.

The coil of solenoid 10 is connected in parallel to the coil of valve 9. One end of the coil is connected to power terminal 44 of power source 46. The other end of the coil is connected through a time delay circuit 48, to the line 45 leading to the contacts of manometer 8 and the other terminal 50 of power source 46. Time delay circuit 48 is of the type in which the delay time for closing may be set at any desired value, for example 3 minutes for a purpose hereafter explained in connection with the description of the operation of the system.

One end of the coil of solenoid valve 14 is connected to one power terminal 44; the other end of the coil is connected to the other power temiinal 50 through the contacts of a manometer 15. These contacts are so connected that they are closed in response to a drop of pressure within gas container 2 from the operating pressure. Valve 14 is normally closed; energization of its coil opens the valve. In the open position valve 14 has a much smaller cross section than valve 9. Accordingly it may be used to accommodate slight pressure drops of, for example l2 atmospheres gauge within the operating pressure container 2.

Manometer 15 is arranged so that its contacts are closed in response to a smaller pressure drop than that which closes the contacts of manometer 8.

OPERATION OF THE PREFERRED EMBODIMENTS After the system has been started and brought into equilibrium the pressure within gas container 2 is 25 atmospheres gauge, and that within the intermediate receptacle 7 and the reservoir 6 is approximately 200 atmospheres gauge.

When the switch control, not shown, is tripped gas is supplied from the container 2 to the actuator to initiate a switching action. The drop in pressure'within container 2 is sensed by manometer 8. The manometer contacts close to thereby open solenoid valve 9. The contents of intermediate receptacle 7 discharge through valve 9 and the throttle 12 which reduces its pressure to the operating pressure of 25 at mosplieres gauge. The gas at this pressure is delivered to container 2 and brings its pressure back to the operating level. While some gas passes from the reservoir 6 to the receptacle 7 through the open valve 10, the throttle 11 tends to sufficiently delay this passage so that the pressure within reservoir 6 has no significant effect on gas container 2. The pressure in container 2 increases much less steeply toward the end of the flow than at the beginning when the intermediate reservoir 7 is full the pressure change follows an exponential function. The complete pressure equalization occurs comparatively slowly so that sufficient time is available to regulate the replenishing member.

A return of the pressure within gas container 2 back to the operating pressure opens manometer 8 and solenoid valve 9 again closes. I T

The throttle 11 has a passage of such cross section that replenishment of the intermediate receptacle 7 takes approximately 3 minutes. The throttle 12 disposed between the intermediate receptacle 7 and gas operating container 2 serves to regulate the pressure increase in such a manner that dangerous pressures are avoided within the supporting insulator connection 3, and a replenishment of pressurized air into the container 2 occurs in less than the minimum momentary interruption time, for example in less than 0.2 seconds.

Should the pressure within gas container 2 fail to return to the full operating pressure within'the time set at time delay circuit 48, for example 3 minutes, this will be evidenced by continued closure of the contacts of manometer 8 for more than that period of time, and ehergization of the coil of solenoid valve occurs to close this valve. This prevents the compressor from continuously running.

Continued closure of the contacts of manometer keeps solenoid valve 14 open and the intermediate receptacle 7 then gradually completes the work of bringing gas container 2 back to its full operating pressure. When this is done manometer contacts 8 close as does valve 10 and the intermediate receptacle is brought back to its full pressure since both valves 14 and 9 then are closed.

Should the pressure within the container 2 reach a dangerously high value at any time during operation safety valve 13 will relieve this pressure thus preventing overload on the insulator connector 3 or the gas container 2 or its switch. Such operating pressure rises may occur should the manometer 8 fail Small pressure drops within the operating container 2 such as may occur at a unipolar temporary interruption of a three pole pneumatic switch or with a pneumatic switch in which the switching path is weakly blown open during the switching off of operating currents will be compensated for by opening of the magnetic valve l4.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations.

I claim:

1. A gas operated electrical switch for use in opening and closing high voltage electrical lines, comprising, in combinaon: n a. switch means for opening and closing a high voltage electrical line; b. gas pressure actuated means for actuating said switch means; I

c. gas container means containing gas at the operating pressure for said actuating means in sufficient quantity for one switching action connected to supply gas to said actuated means; d. high pressure gas reservoir means holding gas at a pressure which is a multiple of said operating pressure and in a quantity sufficient for a large number of switching operations;

e. gas pressure reducer means connecting the said reservoir and container means for reducing pressure from said high pressure, to said operating pressure, said gas pressure reducer means including a small intermediate receptacle for holding gas at substantially the same pressure as said high pressure reservoir and containing a quantity of gas which just suffices to replenish the pressure in said container to its operating pressure after a first switch actuation to thereby permit a second switch actuation immediately thereafter.

2. The combination defined in claim 1 wherein said intermediate receptacle is forrned of a plastic material reinforced with glass fibers.

3. The combination defined in claim 1 including solenoid valve means located between said intermediate receptacle and said gas container means, and means responsive to the pressure within the said gas container means for operating said solenoid valve means.

4. The combination defined in claim 1 including solenoid valve means controlling the flow between the said reservoir means and the intermediate receptacle, and time delay means for delaying the operation of said valve means until recharging of said container means by the intermediate receptacle has been completed.

5. The'combination defined in claim 1 including throttle means disposed in the means connecting the reservoir and the receptacle and the means connecting the receptacle and the gas container means to control the time at which pressure rises within the container means and the receptacle.

6. The combination defined in claim 5 wherein said throttle means are solenoid valves whose passage cross section serves as a choke when they are in the open position.

7. The combination defined in claim 3 wherein the solenoid means is bypassed by a line controlled by a second solenoid valve means, and means responsive to small drops in pressure in the gas container means for actuating said second solenoid valve means.

8. The combination defined in claim 1 wherein said gas container means is electrically connected to a high voltage electric line and is at a high voltage potential, and said reservoir means is electrically insulated from said container means and is held at a ground potential.

9. The combination defined in claim 1 wherein said intermediate receptacle has a volume such that it supplies air in a quantity sufficient to replenish the container means for one switching actuation only. 

1. A gas operated electrical switch for use in opening and closing high voltage electrical lines, comprising, in combination: a. switch means for opening and closing a high voltage electrical line; b. gas pressure actuated means for actuating said switch means; c. gas container means containing gas at the operating pressure for said actuating means in sufficient quantity for one switching action connected to supply gas to said actuated means; d. high pressure gas reservoir means holding gas at a pressure which is a multiple of said operating pressure and in a quantity sufficient for a large number of switching operations; e. gas pressure reducer means connecting the said reservoir and container means for reducing pressure from said high pressure, to said operating pressure, said gas pressure reducer means including a small intermediate receptacle for holding gas at substantially the same pressure as said high pressure reservoir and containing a quantity of gas which just suffices to replenish the pressure in said container to its operating pressure after a first switch actuation to thereby permit a second switch actuation immediately thereafter.
 2. The combination defined in claim 1 wherein said intermediate receptacle is formed of a plastic material reinforced with glass fibers.
 3. The combination defined in claim 1 including solenoid valve means located between said intermediate receptacle and said gas container means, and means responsive to the pressure within the said gas container means for operating said solenoid valve means.
 4. The combination defined in claim 1 including solenoid valve means controlling the flow between the said reservoir means and the intermediate receptacle, and time delay means for delaying the operation of said valve means until recharging of said container means by the intermediate receptacle has been completed.
 5. The combination defined in claim 1 including throttle means disposed in the means connecting the reservoir and the receptacle and the means connecting the receptacle and the gas container means to control the time at which pressure rises within the container means and the receptacle.
 6. The combination defined in claim 5 wherein said throttle means are solenoid valves whose passage cross section serves as a choke when they are in the open position.
 7. The combination defined in claim 3 wherein the solenoid means is bypassed by a line controlled by a second solenoid valve means, and means responsive to small drops in pressure in the gas container means for actuating said second solenoid valve means.
 8. The combination defined in claim 1 wherein said gas container means is electrically connected to a high voltage electric line and is at a high voltage potential, and said reservoir means is electrically insulated from said container means and is held at a ground potential.
 9. The combination defined in claim 1 wherein said intermediate receptacle has a volume such that it supplies air in a quantity sufficient to replenish the container means for one switching actuation only. 